Urberg M, Zemel M B
Metabolism. 1987 Sep;36(9):896-9. doi: 10.1016/0026-0495(87)90100-4.
Impaired glucose tolerance results from Cr restriction in animals, and Cr supplementation improves glucose tolerance in diabetic animals. These effects are presumably due to the role of Cr in glucose tolerance factor (GTF), a complex of Cr and nicotinic acid believed to facilitate insulin binding. Humans, however, do not uniformly respond to Cr supplementation. The present study was designed to evaluate the possibility that the failure results from inadequate levels of dietary nicotinic acid to serve as substrate for GTF synthesis. Sixteen healthy elderly volunteers were divided into three groups and given either 200 micrograms Cr, 100 mg nicotinic acid, or 200 micrograms Cr + 100 mg nicotinic acid daily for 28 days and evaluated on days 0 and 28. Fasting glucose and glucose tolerance were unaffected by either chromium or nicotinic acid alone. In contrast, the combined chromium-nicotinic acid supplement caused a 15% decrease in a glucose area integrated total (p less than .025) and a 7% decrease in fasting glucose. None of the treatments exerted any effect on fasting or one-hour insulin levels. Thus, these data suggest that the inability to respond to chromium supplementation may result from suboptimal levels of dietary nicotinic acid.
动物体内铬缺乏会导致糖耐量受损，而补充铬可改善糖尿病动物的糖耐量。这些作用可能归因于铬在糖耐量因子（GTF）中的作用，GTF是一种铬与烟酸的复合物，被认为有助于胰岛素结合。然而，人类对补充铬的反应并不一致。本研究旨在评估这种无反应是否是由于膳食烟酸水平不足，无法作为GTF合成的底物所致。16名健康老年志愿者被分为三组，分别每天给予200微克铬、100毫克烟酸或200微克铬+100毫克烟酸，持续28天，并在第0天和第28天进行评估。单独的铬或烟酸对空腹血糖和糖耐量均无影响。相比之下，铬与烟酸联合补充剂使葡萄糖曲线下面积总和降低了15%（p<0.025），空腹血糖降低了7%。所有治疗对空腹或1小时胰岛素水平均无任何影响。因此，这些数据表明，对补充铬无反应可能是由于膳食烟酸水平欠佳所致。
